In recent years, the importance of optically active compounds has been significantly growing in the fields of, for example, medicine, agricultural chemicals, food, flavors, and liquid crystals. In particular, in the field of medicine, the following facts have been known: only one optical isomer may show a pharmacological effect, there may be a difference in extent between the pharmacological effects of the optical isomers, or the pharmacological effects themselves may be different from each other. In view of such circumstances, it has been a serious problem to secure a needed optically active compound as inexpensively and stably as possible.
Under the above-mentioned need, a technique for separating optical isomers by high performance liquid chromatography (HPLC) is expected to be one method of securing only a needed optically active compound inexpensively and stably. It has been heretofore known that polysaccharide derivatives each have an excellent ability to separate optical isomers (for example, Patent Documents 1 and 2).
Optical isomer separating fillers comprising the polysaccharide derivative have the following characteristics: each kind of the fillers can separate a large number of optical isomers and is excellent in general-purpose property. However, not all the optical isomers that exist in the world can be separated with one kind of an optical isomer separating filler, so the filler and optical isomer separating filler as described below have been developed: a filler having a separating ability by which optical isomers that cannot be separated with existing fillers can be separated and an optical isomer separating filler having a separating characteristic different from those of the existing fillers.
The modification of a hydroxyl group or amino group of a polysaccharide with a compound having a characteristic structure has been performed as one approach to providing a filler having a separating ability and separating characteristic different from those of the existing fillers. For example, a filler using a halogen-substituted aromatic carbamate derivative of a polysaccharide obtained by modifying a hydroxyl group or amino group of the polysaccharide with an aromatic compound, a part of which is substituted with a halogen as an active ingredient, has been developed, and it has been revealed that the filler has a separating characteristic different from that of a non-halogen-substituted aromatic carbamate derivative of a polysaccharide (Patent Document 3).
In addition, the following approach has been performed: a solvent-resistant filler capable of using even a solvent that dissolves a polysaccharide derivative as a mobile phase is developed by chemically bonding the polysaccharide derivative to a support, or by crosslinking the molecules of the polysaccharide derivative carried by the support so that the filler may be applicable to an additionally wide range of separation conditions, and can separate optical isomers that cannot be separated with existing optical isomer separating fillers. In view of the foregoing, various solvent-resistant fillers have been developed. Examples of methods of chemically bonding a polysaccharide derivative to a support include: a method involving causing the support to carry the polysaccharide derivative physically and irradiating the resultant filler with light to immobilize the polysaccharide derivative chemically (Patent Document 4); a method involving chemically bonding a reducing terminal of the polysaccharide derivative to the support (Patent Document 5); and a method involving introducing a polymerizable group into each of the polysaccharide derivative and the support and copolymerizing the polysaccharide derivative and the support in the presence of a third component having a polymerizable group to chemically bond the polysaccharide derivative and the support (Patent Document 6).
As described above, optical isomer separating fillers having various separating abilities and separating characteristics have been developed. However, the fact remains that optical isomers that cannot be separated, even with various optical isomer separators, are still present, so the further development of an optical isomer separating filler having a separating ability and separating characteristic different from those of conventional products has been demanded with a view to enabling the separation of such optical isomers.    Patent Document 1: JP 60-142930 A    Patent Document 2: JP 63-178101 A    Patent Document 3: JP 61-233633 A    Patent Document 4: JP 11-510193 A    Patent Document 5: JP 07-138301 A    Patent Document 6: JP 2002-148247 A